Fixing bug where sampling number of blocks could be less than number …

…of blocks to read

datadriver/datablocker.py

@@ -91,6 +91,12 @@ def get_blocks(self, records):
         return [records[indices : indices + block_size] for indices in range(0, num_records, block_size)]
 
 
+def _sample(dataset, sample_num):
+    if len(dataset) < sample_num:
+        return dataset
+    else:
+        return random.sample(dataset, sample_num)
+
 class ResamplingBlocker(object):
     @staticmethod
     def get_blocks_gamma(records, num_blocks, block_size, gamma):
@@ -108,7 +114,7 @@ def get_blocks_gamma(records, num_blocks, block_size, gamma):
         nonfull_blocks = range(num_blocks)
 
         for record in records:
-            for block_no in random.sample(nonfull_blocks, gamma):
+            for block_no in _sample(nonfull_blocks, gamma):
                 blocks[block_no].append(record)
                 if len(blocks[block_no]) >= block_size:
                     # Remove block from contenders list if block is